Not everyone living in the Paleolithic era produced children. Many died before reaching reproductive age, some undoubtedly were infertile, some would have failed to mate, and so on. Nevertheless, we all once lived in kinship societies, which means that children were in close proximity — and available to be helped — over nearly the entirety of our evolution.
And there’s a lot of evidence indicating that children were helped, significantly and often, and with adaptive outcomes. My own work on Ifaluk, a kinship society in Micronesia, was among the first to build this case, and it’s since been built and rebuilt many times, probably most thoroughly for the Hadza by Kristin Hawkes and colleagues.1,2 In fact, due to these field studies, and some bridging arguments from life history theory, it seems pretty certain that we have a maximum potential lifespan twice that of other apes (living and extinct), because our reproductive utility was extended to older and older ages, not so much by direct reproduction, but by helping.3
But that’s old news. The new point I want to make is that this longstanding path to reproductive success has been curtailed by modernization, thus creating an evolutionary mismatch that I believe contributes significantly to our modern-day epidemic of sadness.
To be clear, I’m not suggesting that our mission in life should be maximizing reproductive success. Evolutionary theory explains, and it sometimes gives insight that can be useful with respect to the choices we make, but it doesn’t force our hand, and it doesn’t possess a moral compass. Furthermore, it is obviously possible to be happy without reproducing, and the argument to follow is not meant to imply otherwise.
These caveats aside, how sad are we? A recent Lancet article estimates that globally 350 million people suffer from a depressive disorder, and to put a finer point on it, 6.5 million of 35 million Americans aged 65 or older are depressed.4,5 These are surprisingly large numbers, I think, especially given that based on many objective criteria, we are living in the best of times.6,7
So, what accounts for the soaring prevalence of sadness in modern societies? One might surmise from their prescribing habits that most physicians believe we should be happy but aren’t, because something’s wrong with the chemistry of our brains, so “take a selective serotonin reuptake inhibitor and . . . call when you need a refill.” But there’s an alternative explanation — one that I believe applies far more broadly than the malfunctioning neurochemistry paradigm. It is that our brains are working as they were designed to work, and we’re sad, because we increasingly choose to behave in ways that fail to help our cause. The premise is that sadness, like all other emotions, evolved to steer our behavior in adaptive directions, which is also true of our senses. Touch the hot stove, and you’ll reflexively pull back your hand, and probably remember not to do that again; and even though pain was part of the process, you’ll likely be happier over the long run for having learned that lesson.
So, what’s gone wrong? Why is our intricately designed emotional feedback circuitry so frequently failing us? Pharmaceutical approaches that ignore the evolved function of emotions probably contribute (see above), but I believe the larger problem is that modernization has altered our social options in ways that have a lot of upsides, but also some downsides.
The central claim of this essay is that our newfound ability to choose to live an unconnected life — a life without dependents — is particularly laden with downsides. Trouble awaits, because helping children, grandchildren, nephews, nieces, more distant relatives, and on occasion the foraging band as a whole (which we all once lived in) would not have become a sustained theme in our ancestor’s lives if it were not for mechanisms that coevolved to instigate and direct that behavior. In other words, there must be many ancient "buttons" inside our heads that, when pushed, make us feel useful, fulfilled, satisfied, or in a word, happy, and for many of us they are no longer being pushed often enough or hard enough, because we no longer live in kinship societies.
What’s the remedy? Not everyone has children and grandchildren, nor can everyone live near them. But there are options for all of us that will, if my reasoning is sound, push some of these happiness buttons in our heads more often and harder than they are currently being pushed. Clearly, there’s no shortage of need out there, and I believe that helping children, whether they are related to us or not, is almost certainly a more potent inducer of happiness than taking care of the house plants. And I’d venture that puppies work better than gold fish. So, steps can be taken, big and small, by almost everyone.
I’m going to leave it at that, except for one anecdote. In nursing homes and other assisted living arrangements for the elderly, the residents are increasingly being given baby dolls to hold and care for. It seems to make them happy.8 Imagine what a real child can do.9
References
1. S.B Hrdy. 2009. Mothers and Others. Belknap Press of Harvard University Press, Cambridge, MA.
2. M.G. Thomas et al. 2018. Kinship underlies costly cooperation in Mosuo villages. Royal Soc open sci. 5:171535
3. P.W. Turke. 1988. Helpers at the nest: childcare networks on Ifaluk. In Human Reproductive Behavior, L. Betzig, M. Borgerhoff Mulder, and P. Turke, eds. Cambridge University Press. Cambridge, UK.
4. https://www.ncoa.org/wp-content/uploads/Depression_Older_Persons_FactSh…
5. A. Cipriani et al. 2018. Comparative efficacy and acceptability of 21 antidepressant drugs for the acute treatment of adults with major depressive disorder: a systematic review and network meta-analysis. Lancet, online first, http://dx.doi.org/10.1016/ S0140-6736(17)32802-7
6. S. Pinker. 2011. The Better Angels of Our Nature: Why Violence has Declined. Viking Books.
7. M. Ridley. 2010. The Rational Optimist: How Prosperity Evolves. Harper-Collins, New York, NY.
8. https://www.simplemost.com/nursing-homes-considering-doll-therapy-resid…
9. https://www.psychologytoday.com/blog/bringing-baby/201705/if-you-wanna-…